1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a projection-type display, and more particularly, to a projection-type display apparatus in which the surface area of a substrate forming a reflection unit varies as to prevent deformation when the temperature rises, and a display method thereof.
2. Description of the Related Art
A display apparatus projects a video signal including red, green, and blue (R, G, B) color signals onto a screen to display a video. Cathode ray tube (CRT) display apparatuses were widely used in the past, but more recently, a projection-type display apparatus has become more widely used. Digital light processing (DLP) display apparatuses have been developed as a third generation of projection apparatuses.
DLP display apparatuses use a semiconductor chip known as a digital micromirror device (DMD) including more than 1.3 million mirrors, in which each mirror is capable of being controlled, separately. The projection-type display apparatus adjusts a slant angle of the DMD, and projects a ray consisting of R, G, B rays corresponding to a desired color onto a projection lens to display a video. The light emitted from the DMD, that is the video, is adjusted by a reflection unit to fit to the size of a screen, and is displayed on the screen. The reflection unit includes a projection lens, projection mirror, and glass. A surface of a plastic substrate is coated with mirrors to form the reflection unit.
A related art DLP display apparatus reflects a video output from a DMD using a reflection unit and displays the video on a screen. The reflection unit absorbs a part of the light reflected therefrom, causing the temperature of the substrate to rise, and the area of the substrate to expand. Consequently, the surface area of the substrate varies, and the direction of the light reflected from the reflection unit to the screen is changed. That is, a focus of the video scanned from the DMD onto the screen is changed by the reflection unit.